Abstract. Enhanced efficiency fertilizer (EEF) technologies that employ product coatings to delay nitrogen (N) release or are chemically stabilized to inhibit key steps of N transformations in soil offer potential for improving N use efficiency (NUE) in agricultural systems. However, the dynamics of N release and transformation from single technologies may result in a spatial or temporal mismatch of N supply and demand during a growing season. This may be overcome by use of blends of different technologies, provided the reduction in the concentration of stabilizing products does not reduce effectiveness. Laboratory incubations quantified the N dynamics around bands of controlled-release fertilizer (CRF) and nitrification-inhibited (NI) urea and varying blends of these technologies and referenced this against conventional urea and biodegradable, plant-oil-coated urea (POCU) applied at the same rates in two contrasting soils over 60 d. Blends of NI urea (3,4-dimethylpyrazole phosphate, DMPP urea) and a CRF (polymer-coated urea, PCU) typically resulted in N concentrations and distribution that were intermediate to those of the constituent products in unblended applications. Changes in the proportions of each product were mirrored by urea nitrogen (urea-N) concentrations around the bands in both soils, while the proportions of DMPP urea in each blend were only related to the extent of nitrification inhibition in the Vertisol. A proportion of the POCU granules burst during the early stages of incubation, resulting in initially higher mineral N concentrations compared to PCU. However, both CRFs delayed N release and formation of nitrate nitrogen (NO3-N) relative to granular urea, and mineral N distribution was similar within each soil. Soil type had a significant impact on banded N dynamics. Where there was little effect of N-fertilizer treatment on NO3-N production in the Ferralsol, the higher impedance to solute transport in the Vertisol contributed to a significant inhibitory effect of NI urea on nitrification in both pure and blended DMPP urea treatments. Using NO3-N production as a benchmark for the risk of environmental loss, the efficacy of fertilizer treatments in this soil was of DMPP urea / PCU blends (higher ratio of PCU may offer small but insignificant benefit) > DMPP urea = PCU > urea. These findings highlight the importance of soil properties in determining the N dynamics from different banded EEF products. Insights into the efficacy of biodegradable alternatives to polymer coatings and the efficacy of blended EEF products can improve the reliability of N supply while reducing environmental impacts, therefore offering greater opportunities to sustainably improve fertilizer NUE in cropping systems.

中文翻译：

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对比施肥技术对“纯”或混合施肥地下带氮动态的影响

摘要。增效肥料 (EEF) 技术采用产品涂层来延迟氮 (N) 释放或化学稳定以抑制土壤中氮转化的关键步骤，这为提高农业系统中的氮利用效率 (NUE) 提供了潜力。然而，单一技术的 N 释放和转化动态可能导致生长季节 N 供需的空间或时间不匹配。这可以通过使用不同技术的混合物来克服，前提是稳定产品浓度的降低不会降低有效性。实验室孵化量化了控释肥料 (CRF) 和硝化抑制 (NI) 尿素以及这些技术的不同混合物带周围的 N 动态，并将其与传统尿素和可生物降解的尿素进行比较，植物油包覆尿素 (POCU) 在两种对比土壤中以相同比例施用超过 60 天。NI 尿素（3,4-二甲基吡唑磷酸盐，DMPP 尿素）和 CRF（聚合物涂层尿素，PCU）的混合物通常会导致 N 浓度和分布处于未混合应用中成分产品的中间值。两种土壤中条带周围的尿素氮 (urea-N) 浓度反映了每种产品比例的变化，而每种混合物中 DMPP 尿素的比例仅与 Vertisol 中的硝化抑制程度有关。一部分 POCU 颗粒在孵化早期破裂，导致最初的矿物质 N 浓度高于 PCU。然而，相对于颗粒尿素，两种 CRF 都延迟了 N 释放和硝态氮 (NO3-N) 的形成，每种土壤中的矿质 N 分布相似。土壤类型对带状氮动态有显着影响。在氮肥处理对 Ferralsol 中 NO3-N 产生几乎没有影响的地方，Vertisol 中对溶质传输的更高阻抗导致 NI 尿素在纯和混合 DMPP 尿素处理中对硝化作用的显着抑制作用。使用 NO3-N 产量作为环境损失风险的基准，肥料处理在该土壤中的功效为 DMPP 尿素/PCU 混合物（更高比例的 PCU 可能提供小但微不足道的好处）> DMPP 尿素 = PCU > 尿素。这些发现强调了土壤特性在确定来自不同带状 EEF 产品的 N 动态方面的重要性。